Jonathan at TLD ran a series of benchmarks on the 6-core Mac Pro vs quad-core iMac. I've got an argument against Apple using Xeon CPUs in terms of value, however, the new Mac Pro seems to stack up OK. Roughly it seems the Mac Pro score about 30-40% faster and it's about 30% more expensive. Where things can get sticky is the iMac of course includes a 27-inch display, but the Mac Pro incorporates dual workstation-class GPUs. Desktop GPUs are generally faster than the mobile GPUs in the iMac, but the Mac Pro also two of them. In addition to that there's greater external expansion and other stuff, but strictly on CPU and GPU performance, these tests indicate this Mac Pro stacks up reasonably vs the top end iMac on performance per dollars.